Electron discharge device



Feb. 10, 1942, J. H. JONKER Y 2,272,844

ELECTRON DISCHARGE DEVICE 'Filed Dec. 17-, 1938 0$TPUT I INVENTOR. JOHAN L. H. JONKER BY WW woman Patented Feln 10, -1942 ELECTRON DISCHARGE DEVICE Johan Lodewijk Hendrik Jonker, Eindhoven, Netherlands, assignor, by mesne assignments, to Radio Corporation of America, New York,

N. Y., a corporation of Delaware Application December 17, 1938, Serial No. 246,288 In the Netherlands January 8, 1938 1 Claim.

Thisinvention relates to elect ron discharge tubes whose characteristic curve has a variable slope, that is a so-called "variable ,1. tube.

. Various means have already been utilized for,

obtaining discharge tubes having such a characteristic curve. Thus, it is known to utilize grids whose pitches vary in the direction of the length. Besides, it is possible to utilize difierent pitches for different-portions of the grid, or plate-shaped grid-electrodes which have apertures of difierent sizes.

The operation of-tl'lis known form of construction is based on the fact that the grid portions which have comparatively small apertures have a stronger'controlling efiect and consequently, with an increasing negative voltage, retain the electron stream sooner than the portions of the grid which have larger apertures.

It is the principal object of my invention to provide an improved electron discharge device having a variable a characteristic.

from the cathode into beams and to train them on these slits or apertures.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claim, but the invention itself will best be understood by reference to'the following description taken in connection with the accompanying drawing in which Figure 1 represents diagrammatically an embodiment of my invention wherein the deflecting electrodeis formed as a grid while ineach of Figures 2 and 3 is diagrammatically shown an electron discharge device embodying my invention and of different construction.

Referring to Figure 1, a cathode I has adja-. cent it a positive deflecting or dispersing electrode 2 which may be formed as a grid or may The present invention relates to means which result in the desired variable slope according to a quite different principle. According to the invention, there is arranged between the control grid and the cathode an electrode which has a positive potential with respect to the cathode and which causes strong dispersion of part of the electrons, with the result that the electrons which pass through this electrode at a substantially equal speed, reach thecontrol'electrode at difierent speed components, in the direction of this control electrode. The electrons which travel in the middle of the apertures or slits of the deflecting or dispersing electrode can con- 1 tinue their paths substantially rectilinearly and consequently reach the control electrode on the shortest path and therefore also at the highest speed whereas the electrons at the edges follow a curved path and consequently lose more speed in the direction of the control grid since the deflecting electrode is maintained at a positive potential and the control electrode, on the contrary, at a negative potential. When the negative voltage of the control electrode increases the electrons moving at comparatively low speed are consequently retained first and sent back to the positive deflecting electrode with the result that the desired control characteristic is obtained without any necessity of utilizing irregularly wound electrodes. 1 v

The deflecting electrode may be formed as a grid but it may also have the shape of a cylinder or disc having one or moreslits, in which event "it is advantageous to form the electrons coming consist of a plurality of rings or'cylinders ar-' ranged, at some distance from one, another, so

as to be co-axialwith respect to the cathode followed by control electrode 3, screen grid 4 and the anode 5 of the tube all within an envelope l2. It is not necessary to utilize a screen grid and, on the other hand, it is also possible to provide a plurality of grids The control grid 3 is shown with a constant pitch. All the electrodes may be. coaxial.

As is indicated by the arrows, the electron paths which initially extend substantially paral-' lel or radial are deflected or dispersed due to the edge-effect of the apertures in the grid 2, so that the paths which the electrons have to follow to reach the control grid 3 are of. diiferent lengths.

In the form of construction according to Figure 2 the electrons which leave the cathode 6 are formed into. beams, for example by means of a negative electrode 1. The beam which is directed on to the aperture in the deflecting or, dispersing electrode 8 is diffused due to the field at the edges. The control grid ,9 and the screen grid Ill are positioned between electrode 8 and the anode H. The electrodes are enclosed in envelope l3. I

The electrode 8 may also consist of two or more cylindrical members which are arranged. some distance apart from one another and so as to be coaxial with respect to the cathode and provided with slits. It may also be constituted, however, by a cylinder having a longitudinal slitor slits which are parallel to the cathode as shown in .ments of my invention of which I am now aware for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used andthe purpose for which it is employed without departing from the scope of my invention as set forth in the appended claim.

What I claim as new is:

An electron discharge device having a cathode for supplying electrons and an anode for receiving said electrons, a control grid positioned between the cathode and anode having a constant pitch between turns and an auxiliary grid electrode positioned between the cathode and control grid and comprising flat ribbon-like elements spaced along the cathode at comparatively wide intervals with respect to the intervals of the con- :trol grid, an input circuit connected to said control grid and an output circuit connected to said anode, and means for maintaining said auxiliary grid electrode at a positive potential with respect to the cathode and control grid'i'or providing a plurality of dispersed beams oi electrons between said auxiliary grid electrode and said control mid.

JOHAN LODEWIJK I-mNDRIK JO. 

